Cell division and cancer

Specialised cells

Epithelial cells

Cell membrane

The membrane which forms the boundary between the cytoplasm of a cell and the medium surrounding it and controls the movement of substances into and out of the cell.

Mitochondria

Organelle(s) within cells that produce ATP, used as a store of chemical energy. Often called the cell's powerhouse

Radiation

The emission of heat, light or other electromagnetic waves.

Receptors

Protein molecules attached to cells that only bind to specific molecules with a particular structure

Diffusion

The spreading out of the particles of a gas or any substance in solution down a concentration gradient

Pancreas

An endocrine gland which produces insulin

Vesicle

Small sac that stores or transports substances inside a cell

Membrane

A thin, flexible sheet-like structure that acts as a lining or a boundary in an organism.

Insulin

A hormone produced by the pancreas. It allows cells in the body to take in and store glucose.

Osmosis

The movement of water through a partially permeable membrane down a concentration gradient from a dilute solution (where there is a high concentration of water) to a concentrated solution (where there is a relatively low concentration of water).

Gland

A group of cells which produce and secrete a particular substance. Many glands pass their secretions into a tube or duct, whereas endocrine glands secrete hormones directly into the blood.

Nerve

A bundle of neurones - it may be all sensory neurones, all motor neurones or a mixture of both

Sperm

The male sex cell or gamete. The full name is spermatazoan, abbreviated to sperm cell or sperm.

Cell structure and transport

Humans are multi cellular organisms. That means they are made up of billions of individual cells. These cells are not all the same. There are many different cell types that are specialised to perform the range of functions needed in a complex organism.

Different types of cells

As new cells grow and replicate, they become specialised to do particular jobs. Nerve cells that carry electrical signals, muscle cells which generate force and pancreas cells making insulin are just a few examples. Amazingly, all of these cells have grown from just one single fertilised egg cell.

Ciliated epithelium

Cells like these line the windpipe or trachea. The cell membrane is folded into tiny hairs which can move and push dust particles out of the lungs.

Many types of cancer, including those of the stomach, lung, skin and bowel, start off in epithelial cells. These cells line your organs and tissues and are exposed to environmental influences which, over time, can cause cancer to arise. For example smoking and lung cancer, ultraviolet radiation and skin cancer.

Sperm cell

The sperm cell has a tail so it can 'swim' to fertilise an egg cell. It has lots of mitochondria to generate the energy it needs.

Nerve cell

Nerve cells have branches coming out from the main part of the cell. These can carry nerve signals and connect to other nerve cells, receptors or muscles.

How molecules move in and out of cells

Substances can cross the cell membrane by diffusion, osmosis and active transport. Use the animation to see how each of them works.